<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>css盒子模型</title>
    <link rel="stylesheet" href="css_four.css">
</head>
<body>
    <h1>h1-块级盒子</h1>
    <p>p-块级盒子</p>
    <pre>pre-块级盒子</pre>
    <div>div-块级盒子</div>
    <span>span-内联盒子</span>
    <span>span-内联盒子</span>
    <a href="#">a-内联盒子</a>

    <b>b-内联盒子</b>

    <div class="box_before"></div>
    <div class="box"></div>
    <div class="box_after"></div>

    <div class="box_outline">
        <div class="box_size">1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br>1<br></div>
        </div>


        <div class="box_outline">
            <div class="box_margin"></div>
            <div class="box_margin2"></div>
        </div>

        <div class="box_outline">
            <p>1</p>
            <p>2</p>
            <p>3</p>
        </div>
</body>
</html>